Train control



Patented Sept. 22, 1931 UNITED STATES PATENT OFFICE.

. W'INTHROP K. HOWE, OF ROCHESTER, YORK, ASSIGNOR 'IO GENERAL BAILWASIGNAL COMPANY, OF ROCHESTER, NEW YORK TRAIN CONTROL Application filedSeptember 11, 1924. Serial No. 737,163.

This invention relates to automatic train control systems for railroads,and more particularly to the provision of means requiring the engineerto take appropriate action, conveniently termed acknowledgement, uponthe approach of his train to a stop signal or entrance to a danger oroccupied block, and also thereafter at repeated intervals of time solong as the train is traveling under a stopsignal or in such danger oroccupied block, otherwise the brakes of the train are automaticallyapplied and the train brought to a stop, or some other suitable penaltyenforced. 1

Other objects, purposes and characteristics features of the presentinvention. will appear .as the description thereof progresses.

In describing the'invention' in detail reference will bemade to theaccompanying drawings in which Fig. 1 shows a portion of a typicalautomatic wayside signal system. having train control apparatussuperimposed thereon, together with a vehicle shown conventionallyhaving suitable inductive influence receiving apparatus carried thereby;and

Fig. 2 shows conventionally and in a diagrammatic manner the car-carriedapparatus of the invention.

The present invention, which relates primarily to the acknowledgment ofstop or danger signals, is applicable to train control systems of eitherthe intermittent inductive type or the continuous inductive type. Thisinvention for convenience, however, has been shown applied to a simpleform of a train control system of the continuous inductive type, namelya two-position system in which a two-position main control relay isused.

Referring to Fig. l of the drawings, the reference characters 1designatethe track rails, which are divided by insulating joints 2 intoblocks in the usual way, the block I and the adjacent endsof two otherblocks H and J being shown. f Since the various blocks are assumed to beequipped the same, like parts of each block are designated by likereference characters havingdistinctive for the block I, each of theseblocks is pro= vided with the usual normally closed track circuitincluding a battery 3,'which is connected in series with the usuallimiting resistance 4:- A track relay T responsive to direct current-isbridged across the block at the entrance end thereof.

The train control system illustrated may be used either with or withoutwayside signals; and since such signals may be of any suitable type,semaphore signals Z have been shown conventionally without illustrat ingtheir well known operating mechanism and control circuits. .Although inthe carcarried apparatus hereinafter described no cab signals have beenshown, such cab sig nals may be applied in the usual way, when desired,and especially if no wayside signals are employed.

Alternating current is superimposed on the direct current in the usualtrack circuit and flows down one rail and back through the other, onlywhen traflic conditions ahead are clear. In the particular arrangementshown, a transformer 5, having its secondary winding connected in serieswith the track battery 3, is energized under clear traffic cnditions bycurrent derived from a transmission line 6 through a circuit includingthe front contact 7 of the relay T of the block J next in advance.

On the locomotive or other vehicle, illustrated by the wheels and axles10 and 11, .are two car elementsor receivers in front, each comprising acore of laminatedmagnetic material 12, terminating in enlarged polepieces 13 and provided with a winding 14. These windings 14 areconnected in series in such a manner that voltages induced therein dueto current flowing-down one rail and back through the other arecumulative. These coils 14 are preferably tuned to resonance for theparticular frequency of the alternating current used along the trackwayby a condenser 15 of the proper capacity, so that the potential acrossthis condenser 15 is comparatively high. The voltage across thecondenser 15 supplies the input side of an amplifying device A, whichinexponents. Using the reference characters eludes suitable sourcesofenergy and one or m more amplifying tubes or audions well known in theart of continuous inductive train control and radio telephony. Theoutput leads of this amplifying device A are connected to a main relayMR, which is adapted to control the train in accordance with trafiicconditions ahead, manifested by the presence or absence of alternatingcur rent flowing in the track circuit dir-ctly ahead of'the trainequipped withithis apparatus.

Referring now to Fig. 2, this relay MR controls suitable speedrestricting apparatus of the well known cam and governor type, which isadapted to gradually restrict the speed of the train in accordance withits progress along the trackway under adverse traffic conditions ahead.In the particular arrangement shown, this speed restricting camandgovernor mechanism includes a centrifugal speed responsive device orcentrifuge SD of the well known fly-ball type in which a grooved collar17 moves downwardly on a shaft'18, driven from the wheels of A thevehicle in any suitable manner, as the speed of the vehicle increases,by reason of the fly balls 19' acting by centrifugal force upon thissleeve against the opposing force of a spring 20. To a speed shaft 21 ispinned a bifurcated arm 22 which has pins extend ing inwardly on itsbifurcated end and engaging the groove in the collar 17, so that thisshaft 21 is rocked to a position depending on the speed of the train. Tothe speed shaft 21 are also fixedly secured a speed sec tor 23 and aspeed arm 24. The speed sector 23 is of such construction that it closesthe contacts 25 when the speed is practically zero.

The shaft 18 has. fixed thereto a worm 26 which operatively engages aworm wheel 27, pinned on a rotatable shaft 28, so as to cause rotationof this shaft 28 in accordance with the progress of the train along thetrack. This shaft 28'has secured thereon a pinion 29, operativelyengaging a gear 30 pivotally supported on a stationary pin 31. This pin31 also pivotally supports the bifurcated end of an arm 32; and in thebifurcation of this arm is pivotally supported a gear 33 0011- tinuouslymeshing with the gear 30. This .arm 32 is biased upwardly by a spring34, but is normally held in its lower position (as illustrated) by acamstarter magnet CS acting to attract an armature 35 fastened to thearm .32. Directly above the gear 33 and pinned to a cam shaft 36, is amutilated gear 37. This cam shaft 36 is held in a normal position, thatis, the position in which the mutilated portion of the gear 37 isdiametrically opposite to the gear 30, by an arm 38 pinned to thisshaft'and a tension spring 39. On this cam shaft 36 are fixedly securedpermissive speed cam 40, an acknowledgingsignal cam 41, and anacknowledging cam 42, in any suitable manner, by cross pins.

To the lower and free end of the speed arm 24 is pivotally secured thelower end of a floating lever 45, the other end of Which has pivotallysecured thereto a roller 46 bearing against the cam surface of thepermissive speed cam 40. Adjacent to this cam 40 and on a pin 48 ispivotally supported a sector 47 having an eccentrically located pin 49.In order to cause the sector 47 to move in accordance with the speed ofthe train as compared with the speed set up by the permissive speed cam40, it is only necessary to cause movement of an intermediate point onthe floating lever 45. This has been accomplished by a link connectedfrom an intermediate point on the floating lever 45 to the eccentric pin49 on the sector 47. This sector 47 is biased in a clockwise directionby a spring 51, so that the roller 46 is always urged against thepermissive speed cam 40, whereby the sector 47 assumes a'positiondepending on both the position of the cam 40 and the actual speed of thetrain. The sector 47 is provided with a cutaway portion into which theroller 52 will ride when the speed of the train is in excess of thepermissive speed set up by the speed cam 40, whereby the contacts 53 areopened.

"he acknowledging signal cam 41 is of such a shape that the contacts 55are closed through the medium of the roller 54 when the cam 40 hasrestricted the speed to its ultimate minimum and when this cam hasalmost reached its final run down position. The acknowledging cam 42, onthe other hand, opens the contacts 56 just ashort distance of movementof the train after the contacts 55 have been closed.

As heretofore stated, the present invention contemplates that theengineer is required to operate an acknowledging device at repeatedintervals while running under a stop signal, these intervals beingdetermined by a timing device. In the arrangement shown, this timingdevice comprises a shaft 60 horizontally pivotally supported in anysuitable manner, which is biased into its normal position (as shown), bya gear sector 61 engaging a pinion 62 fixed on this shaft 60, the sector61 being pivotally supported on a pin 63 and being biased in a clockwisedirection by a tension spring 64. This sector 61 is adapted to be movedto its other position (shown dotted) by a lever 65, which is alsopivotally secured on the pin 63, and which is disposed to engage a lug66 projecting back from the gear sector 61. 7

Free on the shaft 60 is an escapement wheel 68, which is adapted to bedriven in one direction by the shaft 60 through the ratchet mechanismcomprising, a ratchet wheel 69, adog or pawl 70 and a spring 71. Thisescapement wheel 68, is driven in a counter-clockwise direction, isretarded'by the pivotally supported pallet 72 having a weighted springarm 73 or pendulum pro; jecting therefrom. The shaft also has pinnedthereto a cam 75, which, in combination with spring contacts 76 and 77,is adapted to close and open certain circuits when this cam assumespredetermined posi tions.

Referring to the operation of this time element, or time controlleddevice, it will be noted that if the engineer raises the handle 65, hewill rock the gear sector 61 in a counter-cloclnvise direction to thedotted position, and in turn operate the cam 75 and the ratchet wheel 69in a clockwise direction. Ifthe engineer then returns the handle to thenormal position, as is necessary to complete a certain circuit aspointed out hereinafter, the gear sector 61 and the cam are moved by thespring 64 away from the dotted position shown, the movement beingretarded by the escapement wheel 68 and pallet 72. If this gradualcounter-clockwise rotation of shaft 60 continues, the pro jection 78first strikes the roller 7 9, thereby closing contacts 76, and shortlythereafter the roller 80 rides into the notch, thereby opening thecontacts 77.

Any suitable means may be employed with this invention to act upon theusual airbrake system and produce an automatic application of thebrakes. For the purpose of this case, it is assumed that such automaticbrake control apparatus will be governed by an electro-pne'umatic valve;and to make clear the manner of automatic control of the brakes inaccordance with this invention, a conventional form of electro-pneumaticvalve EPV has been shown with its control circuits.

The car apparatus alsoincludes a penalty relay PR of any suitableconstruction with two separate windings which is, however, made slowacting by the adoption of any of the well known expedients, such ascopper rings on its cores, so that this relay does not actually open itscontacts until after the lapse of a short interval of time follow ingde-energization'of its windings. For the guidance of the engineer, anacknowledging signal, preferably an audible signal, is automaticallygiven in time to permit the engineer to acknowledge before the brakesare automatically applied. Various forms of signal devices are suitablefor this purpose, and an acknowledging signal Ack. S has been showndiagrammatically.

Operation Normally while the train is traveling under a clear slgnal,the main relay MR' s energized as a result of the amplified 1nflu oncereceived from the flow of alternating "current in the track rails. Withtherelay MR energized, a cam starter magnet CS is also energized by acircuit through a front contact 89 of said relay MR, this circuit beingreadily traced in the drawing. The penalty relay PR is normallyenergized by a stick circuit as follows :Beginning at one terminal of asuitable battery or other source of energy, indicated by the letter B,wire 81, contacts 56, wires 82 and 83,1ela-y PR, wire 84, front contact86 of the relay PR, and wire 87 to the other terminal of said source,indicated by the letter C. The electro-magnetic valve EPV, which acts toapply the brakes when de-energized, is normally maintained energized bya circuit readily traced in the drawing, including the speed-distancecontacts .53 and a front contact 88 of the penalty relay PR.

Under clear traflic conditions maximum normal running speed limit isenforced. Referring to Fig. 2, it will be evident that, after therunning speed of the train exceeds a certain value (assumed to be about60 miles per hour), the lower end of the floating lever 45 is moved sofar to the left, with the cam 40 in its initial position, as to rock thesector 47 downward for enough to open the contacts 53 and deenergize thevalve EPV, thereby applying the brakes. As soon as the running speed ofthe train has been brought below the maximum speed limit, the contacts53 re-close, the valve EPV is again energized, and the engineermayrelease the brakes.

When the train enters a caution block, that is, a block in the rear ofone occupied by another train, the main relay .MR is deenergized,because the alternating current iscut off from the track rails'in thiscaution block; and the cam starter magnet CS is in turn de-energized,thereby bringing gears 33 and 37 into mesh and connecting the cam shaft36 to the wheels of the train so that said shaft is gradually moved inaccordance. with the distance travelled. As the cam 40 is thus graduallyturned, it sets up progressively lower permissive speed limits (seecurve 90 in Fig. 1) until a predetermined minimum speed limit (assumedto be 15 miles per hour) is set up, this minimum speed limitcorresponding to the maximum radius of the cam 40. As the train advancesstill further, the gear 33 rotates idly in the mutilated portion of thegear 37, holdingtlie cam L0 in its ultimate position and maintaining theminimum speed limit. If the train at any time exceeds the permissivespeed limits prescribed by the position of the cam 40, the contacts 53open and de-energize the valve EPV to automatically apply the brakes.This brake application is maintained until the speed has been reducedbelow the existing permissive speed limit, whereupon the valve EPV isreenergized, and the engineer may release the brakes.

At a predetermined distance from the exit end of the caution block, thecam shaft 36 is turned to the point where one of the projections on theacknowledging signal cam 41 engages the roller 54 and acts to close thecontacts The point at which the contacts close is indicated in Fig. 1 bya change in the line 55 from a broken line (contacts open) to a solidline (contacts closed). The closing of the contacts 55 energizes theacknowledging signal Ack. S by a circuit readily seen on the drawings,sounding this acknowledging signal as a warning to the engineer that itis necessary for him to operate the acknowledging device. The contacts55 open after a short distance of travel (see Fig. l) and discontinuethe sounding of the acknowledging signal.

Upon sounding of the acknowledging signal Ack. S, the engineer issupposed to raise the handle 65, moving the sector 61- down andtensioning the spring 64: and then return the handle 65 to the normalposition to close the contacts 95. During this downward movement of thesector 61, shaft and the cam 75 are turned clockwise from the positionshown until the projection 78 and adjacent notch on the cam 75 are inthe position indicated by the dotted lines projection 78, during thismovement, momen tarily closing contacts 76 to energize Ack. S through acircuit which is obvious from the drawings, this energization howeverhaving no useful function at this time. The roller 80 now engages theouter edge of the cam 75 and closes the contacts 77, therebyestablishing an auxiliary stick circuit for the penalty relay PR whichmay be traced as follows :Beginning at B, wire 93, contacts 77, wire 94,contacts 95, wires 96 and 83, relay PR, wire 84, front contact 86 of therelay PR, and wire 87 to C. It will be observed that the engineer mustrestore the handle to the normal position in order to complete theauxiliary stick circuit for the penalty relay PR. Consequently, hecannot retain the contacts 77 closed by fastening the handle 65 in theraised position. In other words, after each movement of the handle 65 towind up the time element device, this handle must be returned to thenormal position, permitting the shaft 60 to be brought back gradually toits initial position under the influence of the spring 64 and open thecontact 77.

Shortly after the contacts 55 are closed to sound the acknowledgingsignal, the contacts 56 are automatically opened by the cam 42, asindicated by the broken and solid line 56 in Fig. 1. The opening ofthese contacts 56 interrupts the normally closed stick circuit for thepenalty relay PR, tending to cause de-energization of this relay andcause an automatic brake application. Since the engineer is assumed tohave been vigilant and operated the acknowledging device, the penaltyrelay PR is maintained by its auxiliary stick circuit above pointed out.The contacts 56 remain open so long as the danger conditions continue,so that the contacts 77 must be kept closed by the engineer, by repeatedmanipulations of the acknowledging device, attention being called to thenecessity for repeating operation of the acknowledging device by theenergization of Ack. S by projection 78 closing contacts 76 on thereturn movement of cam 75, just before the cam reaches its shownposition, in order to avoid deenergization of the penalty relay PR andan automatic brake application.

If the engineer fails to operate the acknowledging device in time, thepenalty relay PR is de-energized a short time after the opening of thecontacts 56, and the brakes are applied. The penalty relay PR, oncede-energized by the opening of its stick circuit, cannot again beenergized until the train is brought to a stop, whereupon the zero speedcontacts 25 close an energizing circuit, readily traced on the drawing,through the lower winding of the penalty relay PR, so that its armatureis attracted to close its front cont-act and re-establish a stickcircuit through either the contacts 56 or 77. If the engineer fails toacknowledge, therefore, the train must be brought to a stop before thebrakes can be released, this constituting the penalty for failure toacknowledge. 7

The point at which the contacts 56 open and cause an automatic brakeapplication, unless the engineer forestalls such ap lication byacknowledgment, is preferably braking distance for the selected minimumspeed from the exit end of the block, so that such brake application forfailure to acknowledge will bring the train to a stop before reachingthe end of the block, as indicated by the curve 97 in Fig. 1. Since thepoint in the length of the block at which the contacts 56 open is afixed distance from the point where the cam shaft 36 is set intooperation, it will be evident that it is necessary, in order to have thecontacts 56 open at the right point, to de-energize the car relay MR andstart the cam shaft 36 in each block at a predetermined distance fromthe exit end of that block. In practice the length of the several blockson the railroad frequently differ and may be either shorter or longerthan this fixed run-down distance, so that it may be necessary to employcut sections or other recognized expedients to bring aboutde-energization of the main relay MR at the right point with respect tothe exit end of each block, in order to bring the acknowledging point atthe proper place, assuming that it is desired to have the point ofacknowledgment braking dising device is adjusted -know-ledgement.

tance for the minimum speed from the exit end of the block.

As the train advances block into a danger of occupied block, the mainrelay MR remains de-energized, since the alternating current, if appliedto the rails of that block, is shunted by the train ahead, depriving thefollowing train of such current. The minimum speed limit is, therefore,maintained throughout the danger or occupied block. As the trainadvances from the acknowledging point near the end of the caution block,the shaft is being gradually returned by the spring (i l at a ratedetermined by the pallet 72 andescapement wheel 68 and after the lapseof a predetermined interval of time, say a0 or 50 seconds, the cam '75while turning. counter-clockwise reachesthe point where the projection78 engages the roller 79 and' closes the contacts 76 to sound theacknowledging signal Ack. S. The engineer must now raise the handleagain, otherwise the cam. 75 continues its cou-ntercloclnvise movementand opens the contacts 77, whereupon the penalty relay PR isde-energized, since the contacts 56 are still open. When the engineerraises the handle 65, the contacts. 95 are opened, but the penalty relayPR ismade slow acting enoughto aifordsuflicient. time to raise thehandle 65 and return it to the normal position before the front contact86 of this relay actually opens.

From the foregoing it will be evident that the engineer is required tooperate the handle 65,.while traveling in the danger: or occupied block,at repeated intervalsof time, and if he fails to make this recurrentacknowledgement, the train is brought to a stop. The time interval. forwhich the acknowledgis preferably selected to correspond approximatelyto the 1 time takenby aitrain traveling at minimum speed to travel thenormal length of a block, but this is optional, and the time intervalmay be as short or as long aspreferrecl.

lVheneve-r a block. in which the train is running changes to a clearblock, the relay MB is re-energized and the parts of the car equipmentare automatically returned to the normal position. Until this occurs,and so long as'the train is running with the relay MR de-energized,after having passed through one caution block, the engineer is requiredto aclrnowledg-e repeatedly within less than a set interval. oftimeafter the last ac- WVith other forms of con.- trol, such as intermittentor 3-position continuous inductive, the needfor recurrentacknowledgement at successive time intervals ceases as soon as the blockchanges from danger to caution.v The particular embodiment of theinvention shown, requiring the engineer to make successiveacknowledgement after the first caution block until in a from a cautionclearblock, may be said to have the advantage of discouragingtlieengineer from running under caution signals;

If the train should stop after passing the acknowledging point in acaution block, or while in a danger block, the'zero speed contacts 25close awl maintain the lower winding of the penalty relay Pit-energized,so that the engineer is not obliged cooperate the handle 65 repeatedlyso long as thetrain is not moving. Thusfwhen. the engineer stops histrain at a stop signal and waits for that signal to change to caution orto proceed, he is. relieved fromflthe necessity of' operating theacknowledging contactor at repeated time intervals; whereas so long ashe continues to advance in a danger block, he is required'to acknowledgeat recurrent intervals of time.

.In practice tlie device EPV controls the I brakes of the train in sucha manner that the brakes are not released without manual cooperation,even thoughthe device EPV is re-energized. This precaution, is taken sothat, if the engineer should become incapaciated, or for other reasonsbe unable to perform his duties, and the train be brought to a stop byfailure to acknowledge, the brakes will not be automatically releasedeven though the speed contacts25 are closed, and the penalty relay PRand the device EPV are re-energized. I r

An automatic train control system has thus been devised in which theengineer is required to operate a suitable manually operableacknowledging device a distance in the rear of the first danger signal,and if he fails to make such an acknowledging act, the train is broughtto a stop before it reaches the danger signal, and in which the engineeris required to manifest such vigilance at repeated time intervalsthereafter so long as the train is moving under a stop signal in dangerterritor Although the present rather specifically illustrated, this hasbeen done for the purpose of facilitating the disclosure of theinvention, rather than for the purpose of illustrating the preferredform of the invention to'be used in practice,

or indicating the scope of theinvention. For instance, any othersuitable time element device may be used instead of theclockworkmechanism illustrated; and various other changes and modifications maybe made to adapt the invention to the particular car-carried mechanismin connection with which it is to be used, without departing fromthe'scope' of the invention, or the idea of means underlying the same.

hat is claimed as new and desired to be secured by Letters Patent ist 1. In an automatic train control system, vehicle-carried brake controlapparatus comprising a permissive speed means initiated invention hasbeen in response to change in control influences correspondingtounfavorable trafiic conditions ahead, said permissive speed means actingto impose increasingly restrictive speed limits followed by a minimumspeed limit as the vehicle proceeds under said conditions, means forbringing the vehicle to a stop after said minimum speed limit has beenimposed, and manually operable means for preventing such stop ifoperated at successive intervals while said minimum speed limit is ineffect.

2. In an automatic train control system, vehicle-carried brake controlapparatus including a permissive speed device active when initiated toimpose increasingly restrictive speed limits on the vehicle, and tofinally impose a minimum speed limit, means acting to effect anautomatic stop after a given distance of vehicle travel from the pointat which said minimum speed limit was set up, and a manually operabledevice and associated means for preventing said automatic stop if saidmanually operable device is operated ust before reaching such point andat given intervals while the vehole is proceeding at said minimum speed.

,3. In an automatic train control system' of the type in which controlinfluences cor responding to traffic conditions are transmitted from thetrackway to a moving vehicle, car-carried apparatus comprising meansinitiated in response to change of illfluences corresponding tounfavorable traffic conditions ahead for imposing increasinglyrestrictive speed limits in accordance with the progress of the vehicle,and for finally imposing a constant minimum speed limit, a cab signaland means for actuating said cab'signal a given distance of vehicletravel from the point at which said minimum speed limit is imposed,means for causing an automatic brake application a given interval ofvehicle travel from the point at which said cab signal was actuated, anda device for temporarily preventing said automatic stop if actuatedimmediately after the actuation of said cab signal, said device being inpart manually operable.

4. In an automatic train control system, the combination of a speedrestricting device governed in accordance with trafiic conditions aheadand initiated if traffic conditions ahead are dangerous and changing inaccordance with the progress of the vehicle to gradually reduce thepermissive speed at which the vehicle may travel without incurring anautomatic brake application, means for applying the brakes regardless ofthe speed at which the train is travelling and effective a predetermineddistance of travel after said speed restricting device has beeninitiated, and means for preventing said last mentioned means forapplying the brakes effective if actuated at repeated intervals so longas dangerous traffic conditions ahead exist.

5. In an automatic train control system, the combination of a brakesetting appliance means controlling said brake setting appliance inaccordance with the vehicle speed, means requiring the engineer tomanifest his vigilance upon the approach of his train to a signal atdanger and thereafter at repeated intervals by actuating a manuallyoperable device, and means for actuating said brake setting appliance toeffect a brake application regardless of speed if the engineeer fails toactuate said manually operable device when required.

6. An automatic train control system comprising, a brake settingappliance, means for rendering said appliance active if the speed of thetrain is excessive including a permissive speed device and an actualspeed device, and other means for rendering said appliance activeincluding means effective after the train has travelled a predetermineddistance in dangerous territory unless a suitable manually operabledevice is operated at repeated intervals of time so long as dangertrafiic conditions persist.

7 An automatic train control system comprising, a normally energizedstick electroresponsive device which if de-energized effects anautomatic brake application, two independent means for maintaining saiddevice energized one of which is effective so long as the train istravelling in clear territory and a predetermined distance in dangerterritory regardless of the vehicle speed, and the other of which iseffective if a suitable manually operable device is operated at repeatedintervals.

8. An automatic train control system comprising, a normally energizedstick device which if de-energized effects an automatic brakeapplication, two independent means for maintaining said deviceenergized, one of which is effective so long as the train is travellingin clear territory, and the other of which is effectiveif a suitablemanually operable device is operated at repeated intervals and means foreffecting an automatic brake application in clear territory if apredetermined maximum speed limit is exceeded.

9. In an automatic train control system. a normally energized stickdevice which if de-energized effects an automatic brake application, twostick circuits for maintaining said stick device energized, one of saidstick circuits being maintained energized as long as the vehicle istraveling in clear territory and the other of said stick circuits beingmaintained energized if a suitable manually operable device is operatedat predetermined time intervals, and a pick up circuit for said stickdevice closed by speed responsive comprising vehicle carried brakecontrol apparatus controlled in accordance with influenccs received fromthe trackway corresponding to traitic conditions ahead and acting toimpose an automatic stop at a predetermined distance of vehicle travelfrom a pointat which influences corresponding to unfavorable traflicconditions are received, and manually operable means for sub stituting aminimum speed limit for said automatic stop if operated before saidpredetermined distance has been traversed and at predetermined intervalswhile said influe'nces corresponding to unfavorable traffic conditionsare being received.

11. An automatic train control system comprising a normally energizedbrake applying device which if de-energized effects an automatic brakeapplication, a' permissive speed device active when initiated tode-energize said brake applying device at increasingly restrictive speedlimits, a normally energized stick device acting when de-energized=toole-energize said brake applying device, means for maintaining saidstick device energized while the vehicle is traveling in clear territoryand for a predetermined distance in danger territory, and further meansfor maintaining said stick device energized if a manually operabledevice is operated at predetermined time intervals while the vehicle istraveling in said danger territory.

12. An automatic train control system comprising a normally energizedbrake applying device which if (lo-energized effects an automatic brakeapplication, a permissive speed device for limiting the vehicle speed toa predetermined maximum value when the vehicle is traveling in clearterritory, said permissive speed device being initiated, when thevehicle enters danger territory and acting when initiated to deenergizesaid brake applying device at increasingly restrictive speed limits, anormally energized stick device acting when deenergized to de-energizesaid brake applying device, means for maintaining said stick deviceenergized while the vehicle is traveling in clear territory and for apredeter mined distance in danger territory, and further means formaintaining said stick device energized if a manually operable device isoperated at predetermined time intervals while the vehicle is travelingin said danger territory.

13. In an automatic train control system, the combination of a brakesetting appliance, means requiring the engineer to manifest hisvigilance upon the approach of his train to a signal at danger andthereafter at repeated intervals by actuating a clockwork time releasedevice, and means for movement of said member except in its runactuating said brake setting appliance to effect a brake applicationregardless of speed if the engineer fails to actuate said time releasedevice when required.

14. Railway tralfic controlling apparatus comprising automatic mechanismcarried on a train and operating under unsafe trafiic conditions toapply the brakes, a slow acting device on the train including a contactand requiring periodic manual operation to keep the contact closed, andmeans controlled by said device for preventing an automatic brakeapplication.

15. Railway trafiic controlling apparatus comprising automatic mechanismcarried on Q59 a train and operating under unsafe trafiic conditions toapply the brakes, a normally open contact on the train arranged whenclosed to reopen after a time interval, manually operable means forclosing suchcontact, a second contact controlled by said means, andmeans controlled by said normally open contact and by said secondcontact for preventing an automatic brake application.

16. Railway traific controlling apparatus comprising automatic mechanismcarried on a train and operating under unsafe traffic conditions toapply the brakes, a normally open contact on the train arranged whenclosed to reopen after a time interval, manually operable means forclosing such contact, a second, contact controlled by said means, andmeans controlled by said two contacts and by the speed of the'train for'preventing an automatic brake application. 17. A railway trafliccontrolling system comprising, mechanism on a train automaticallyoperated under predetermined conditions of traffic and speed of thetrain 3'33 to apply the brakes, a slow-releasing electroresponsivedevice effective if not de-energized for more than a limited time tomaintain said mechanism inactive, a normally open circuit for energizingsaid device, a member based to an extreme run down position and actingwhen moved from that posi- 'tion and released to return thereto with auniform slow angular velocity and thereby consume a predetermined timein returning 3515 to its run down position, normally open contacts insaid circuit closed throughout the down position, a handle arranged forconvenient operation by the engineer and ope-rable to move said memberfrom its run down position and close said normally open contacts whensaid handle is shifted from its normal position, and normally closed contacts also included in said circuit and closed only if said handle is inits normal position.

18. In an automatic train control system, in combination with a devicefor initiating a brake application when deenergized, means formaintaining said device eneriii-i l .means located entirely gized itoperated at predetermined time intervals comprising, a shaft biasedtoward a run-down position, means on said shaft for maintaining anenergizing circuit for said device closed until said shai't has turnedto said run-down position, and manually operable means for rewindingsaid shaft.

19. In an automatic train control system, in combination with a devicefor initiating an automatic brake application when deenergized, meansfor maintaining said device energized it operated at predetermined timeintervals comprising a shaft having a retarding mechanism thereon, meansfor biasing said shaft toward a run-down position, contacts operated inaccordance with the position of said shaft and acting to deenergize saiddevice, and manually operable *inding means for turning said shaft awayfrom said run-down position.

20. In an automatic train control system, trackway means fortransmitting influences continuously to a moving vehicle under favorabletraflic conditions only, car-carried apparatus comprising, a device forcausing an automatic brake application when deenergized, means forpreventing an auto maticbrake application comprising a manually actuatedacknowledging means and a member acting to maintain said deviceenergized when in one position, said member being maintained in said oneposition so long as said influences are being received from the trackwayand being otherwise so main tained by the actuation of the acknowledgingmeans at predetermined time intervals.

21. Railway traflic controlling apparatus comprising automatic mechanismcarried on a train and operating under unsafe traflic conditions toapply the brakes, control on the train for preventing an automatic brakeapplication if the engineer take suitable periodic action, andcar-carried indicating means for indicating the time when said periodicaction is first necessary.

22. Railway trafiic controlling apparatus comprising automatic mechanismcarried on a train and operating under unsafe traflic conditions toapply the brakes, control means located entirely on the train forpreventing an automatic brake application if the engineer take suitableperiodic action, and car carried indicating means for indieating thetime when said periodic action .is first necessary, said indicatingmeans being controlled by said control means to indicate when eachrecurrent periodic action is necessary.

23. Railway traflic controlling apparatus comprising automatic mechanismcarried on a train and operating under unsafe traflic conditions toapply the brakes, control nieans protected against misuse and locatedentirely on the train for preventing an automatic brake application ifthe engineer take suitable periodic action, and car-carried i11-dicating means for indicating the time when said action is firstnecessary.

24. Railway traffic controlling apparatus comprising slow-actingautomatic mechanism carried on a train and operating under unsafetrafiic conditions to apply the brakes,

ture.

WINTHROP K. HOWVE.

